Phillip,
I am "tone" deaf. The only C note I recognize is a $100.00 bill. I tighten the blade until I get a nice clear tone when I pluck it with my finger. But for me that does not work when the blade in inserted in the wood then cannot get a clear tone, just a dull thump. For inside cuts I tighten blade until there is a slight give to the left or right when I push on the blade. If you do not purchase a tuning fork, you will have money to purchase more blades.
Larry